Means for casting metals



Nov. 23, 1943. H. v. HlTES MEANS FOR CASTING METALS Filed Jan.v 28, 1943Patented Nov. 23, 1943 UNITED STATES PATENT OFFICE MEANS FOR CASTINGMETALS Hubert V. Bites, Springfield, Ohio, assignor to The Ohio SteelFoundry Company, Lima, Ohio, a corporation of Ohio Application January28, 1943, Serial No. 473,834

i" Claims. 101221-134) This invention relates to the casting of metals,and particularly steel, by the blind head method, wherein the feed metalfor shrinkage in the casting is contained in a so-called blind head orriser and atmospheric pressure is admitted to the interior of the moltenhead metal to relieve a vacuum therein so that proper feed of metal tothe casting to compensate for shrinkage may take place.

While the exact cooling action of molten metal in a blind head during acasting operation is not known, it is reasoned from experience that asthe molten metal rises in a blind head its speed de-- pends on both thesize of the casting cavity to be filled and that of the head cavity,which are proportional in size, andthat the larger the size the slowerthe speed of rise. Also, that the factors tending to cause chilling ofthe head metal and the forming of an air tight skin on its top surface,which prevents proper shrinkage feed, include the volume of air in theblind head cavity which must be expelled through the head wall as themetal rises in and fills the cavity; the area of wall exposed to thecavity; the condition of such wall, i. e., dry or green, and if thelatter the extent of greenness, and the speed of rising movement of themetal in the cavity. These factors are all present to a greater extentin connection with the making of large castings than with small, so thatapparently the tendency to chill and form an air tight skin on the topsurface of the head metal increases substantially in proportion to thesize.

It is also found in practice that fairly good but notentirely dependableresults in maintaining the necessary shrinkage feed in the making ofsmall castings, for instance, those employing blind heads of, or up to,approximately four inches indiameter, have been obtained by the use of acombustible disk-like chill retarding member in the top wall of theblind head cavity with a substantially flat face thereof exposed to theinterior of the cavity and flush with its wall, but that when a similarchill retarding means is used in connection with the top walls of blindOther objects and advantages of the invention will be apparent from thefollowing detailed description, and from the accompanying. drawing,

in whichi Figure 1 is a central vertical fragmentary sectional view of amold of the blind head type embodying the invention, with the moltenmetal at the stage in its upward movement in the blind head cavity whereit first contacts the chill retarding means; Fig. 2 is a view similar toFig. 1, showing the blind head metal as it appears after completeshrinkage feed has taken place; Fig. 3

is a top plan view of the blind head metal after being shaken out from amold and with the portion of the chill retarding means, which remainsafter combustion has taken place, removed from the head, and Figs. 4 andSam different enlarged perspective views of a chill retarding unitembodying, the invention.

Referring to the drawing, I is a conventional showing of a blind headtype of sand mold com-- monly used in the casting of metals and whichhas the customary blind head cavity 2 and the communicating castingcavity 3. Pouring of molten metal into the mold may be effected heads oflarger diameter, the results are not satisfactory. It has also beenfound that such results have not been materially improved and as toproject a distance into the blind head cavity so that the upper end ofthe blind head metal vrising in the blind head during casting will firsthave contact with the protuberant nature of the combustible chillretarding member before com-- through a gate 4 opening into the blindhead cavity 2.

In carrying out the present invention, a core member 6 is mounted in thetop wall of the blind head cavity 2 in exposed relation to theinteriorof such cavity. This core is a unit separate from the mold body andcomprises a disk-like .body part 1 having a substantially flat surface 8from the central portion of which, in spaced relation to its edge,projects a small lug 9, which is preferably but not necessarily circularin cross-section and outwardly tapered. The side edge or peripheral wallof the core is preferably tapered with its large end uppermostto'facilitate retaining the core in place when the mold wall sand ispacked therearound. A core which has been found very satisfactory inpractice for use in connection with both small and large casting moldshas its body 1 approximately two inches in diameter and fiveei'ghths ofan inch thick with the projection 9 approximately one-half inch long andone-half inch in diameter at its lower end. The free radial space fromthe inner end of the projection to the side edge of the disk isapproximately onehalfinch. It will be understood, however, that whilespecific dimensions are given, these are merely for the purpose ofillustration. and not limitation.

The core 6 may be composed of any suitable material which will igniteand burn below the temperature of molten metal, and both coke powder andanthracite coal powder of a finely coarse ground nature packed and boundtogether in a shape retaining mass have been found to be verysatisfactory for the purpose. The combustible material may comprise from30 to 100 per cent of the mass, and this maybe boundtogether by asuitable binder, such, for instance, as oil, a-

cereal binder, and water. If the core contains less than 100% of thecombustible material, the remainder may be of sand. The best results areordinarily obtained, however, by using the full, or substantially thefull, percentage of combustible material. The core material is pressedin a fairly loose manner so as to have a gas permeable characteristicgreater than that of the mold sand to facilitate the passage of airunder atmospheric pressure therethrough, and this characteristic isincreased as combustion of the material takes place.

In use, a core 6 is set into the top wall of a blind head cavity whenthe mold is made, with the surface 8 of the core body I exposed to theinterior of the cavity and substantially flush with its wall and withthe lug or protuberant part 9 projected into the cavity towards thebottom. The usual ventmay be provided from, the top of the head cavity 2through the mold wall, as shown at III by dotted lines, or suchvent maybe and preferably is through an angular passage ll wholly or partiallyinthe core 6, and thence through an upward passage l2 therefrom in themold wall. In. the latter case, the passage I2 is offset from theentrance oftlie passage II to the head cavity so that any loose sand orother matter falling into the p'assagewill be caught by the core 6 andnot fall into the head cavity. A small core-vent I3 is. also providedin'the mold I wall from the core to the outside so as to admit air underatmospheric pressure to the core and through it to the interior of "thehead metal in the blind head cavity.

When molten metal is poured through the gate 4-it fills the castingcavity 3 and at the same time rises in the blind head cavity 2, so thatthe two are filled at, approximately the same time, the full conditionof the mold being indicated by molten metal popping out of the vent 12,as well understood in the art. By the time the head metal I 4 has risento near the top of the head cavity, an air tight skin has begun to formon its exposed top surface and has ordinarily proinvention the topsurface of the head metal first strikes the projected end of the lug 9,causing ignition of the combustible material thereof, and

' as the metal continues to rise around the burning lug, the surfaceskin is stretched and heated thereby and caused to be punctured toprovide an air passage into the interior of the head metal from theoutside. As the metal rises into engagement with the top wall of theblind cavity, it makes contact with the larger bottom surface 8 of thecore body in surrounding relation to the lug 9 so that the entire coreis then ignited and caused to give off heat'to the contacting metalsurface to not only retard further solidifying or skin forming action,but also to render the skin in contact with the surface 8 porous so asto better facilitate the admission of atmospheric pressure to the headmetal. I

gressed to an extent that, unless a puncturing In Fig. 2, I5 designatesa cavity formed in the head metal by admission of atmospheric pressurethereto and indicates that the necessary shrinkage feed of the headmetal has taken place, while in Fig. 3, l6 designates the hole in themetal skin formed by the lug 9, and i1 designates the porous conditionof the thin shell portion of the head immediately around the hole l6 andindicates the effect of the burning contacting core body thereon. Itwill be understood that atmospheric pressure is supplied to the headmetal through the core-vent l3 and core 6.

It is found in practice, for some reason not fully understood, thatdesirable results, not possible by the use alone of a combustibleprojecting of the surface metal and render it porous or pervious to thepassage of air therethrough.

I wish it understood that my invention is not limited to any specificconstruction, arrangement or form of the parts, as it is capable ofnumerous modifications and changes without departing from the spirit ofthe claims.

Having thus described my invention, what I claim as new, and desire tosecure by United States Letters Patent, isr

1. A metal casting mold having a casting cavity and a communicatingblind head cavit a core member having a gas permeable characteristicgreater than'that of ordinary molding sand and including a combustibleingredient which burns upon. contact of molten metal therewith, saidcore having abody part set into the top portion of the head cavity walland forming a part of the inner surface of such wall and having arelatively small central projection therefrom with which molten metalrising in the head cavity first contacts causing ignitionof the corematerial and penetration of the head metal skin before the rising metalmakes contact with said exposed inner surface of the core body, saidhead member in the wall surface. With the present 76 wall havingprovision for admitting air under atmospheric pressure to said coremember.

2. A combination as called for in claim 1 wherein the core body is ofsubstantially fiat disklike form with the central projecting portionforming an abrupt angle with the face of the body exposed to said cavityand spaced from its edge.

wardly from the top wall of the cavity and being of stepped form toprovide difierent surface areas which successively contact the topsurface of metal rising in the upper portion of the cavity and igniteand burn upon contact therewith, the first step serving to puncture themetal skin to admit atmospheric pressure through the core to theinterior molten metal of the head and the final step being substantiallyflush with and forming a continuation of the cavity wall, said head wallhaving provision for admitting air under atmospheric pressure to thecore.

HUBERT V. HI'I'ES.

